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Prerequisites

Installing OpenShift Container Platform with Installer Provisioned Infrastructure (IPI) requires:

  1. One provisioner node with Red Hat Enterprise Linux (RHEL) 8.1 installed.

  2. Three control plane or master nodes.

  3. At least two worker nodes.

  4. IPMI access to each node.

  5. At least two networks:

    1. One network for provisioning nodes

    2. One routable network; and,

    3. One optional management network.

Before installing OpenShift Container Platform with IPI, ensure the hardware environment meets the following requirements.

Node requirements

IPI installation involves a number of hardware node requirements:

  • CPU architecture: All nodes must use x86_64 CPU architecture.

  • Unified Extensible Firmware Interface (UEFI): UEFI boot is required on all OpenShift Container Platform nodes when using IPv6 addressing on the provisioning network. In addition, UEFI device PXE settings must be set to use the IPv6 protocol on the provisioning network NIC.

  • Similar nodes: Nodes should have an identical configuration per role. That is, control plane nodes should be the same brand and model with the same CPU, RAM and storage configuration. Worker nodes should be identical.

  • Intelligent Platform Management Interface (IPMI): IPI installation requires IPMI enabled on each node.

  • Latest generation: Nodes should be of the most recent generation. IPI installation relies on IPMI, which should be compatible across nodes. Additionally, RHEL 8 ships with the most recent drivers for RAID controllers. Ensure that the nodes are recent enough to support RHEL 8 for the provisioner node and RHCOS 8 for the worker nodes.

  • Network interfaces: Each node must have at least two 10 GB network interfaces (NICs)- one for the provisioning network and one for the routable baremetal network. Network interface names must follow the same naming convention across all nodes. For example, the first NIC name on a node, such as eth0 or eno1, should be the same name on all of the other nodes. The same principle applies to the remaining NICs on each node.

  • Registry node: (Optional) If setting up a disconnected mirrored registry, it is recommended the registry reside in its own node.

  • Provisioner node: IPI installation requires one provisioner node.

  • Control plane: IPI installation requires three Control Plane or master nodes for high availability.

  • Worker nodes: A typical production cluster will have many worker nodes. IPI installation in a high availability environment requires at least two worker nodes in an initial cluster.

Network requirements

IPI installation involves several network requirements. First, IPI installation involves a non-routable provisioning network for provisioning the OS on each bare metal node and a routable baremetal network. Since IPI installation deploys ironic-dnsmasq, the networks should have no other DHCP servers running on the same broadcast domain. Network administrators must reserve IP addresses for each node in the OpenShift Container Platform cluster.

Network Time Protocol (NTP)

Each OpenShift Container Platform node in the cluster must have access to an NTP server.

Configuring NICs

OpenShift Container Platform deploys with two networks:

  • provisioning: The provisioning network is a non-routable network used for provisioning the underlying operating system on each node that is a part of the OpenShift Container Platform cluster. The first NIC on each node, such as eth0 or eno1, must interface with the provisioning network.

  • baremetal: The baremetal network is a routable network. The second NIC on each node, such as eth1 or eno2, must interface with the baremetal network.

Each NIC should be on a separate VLAN corresponding to the appropriate network.
Configuring the DNS server

Clients access the OpenShift Container Platform cluster nodes over the baremetal network. A network administrator must configure a subdomain or subzone where the canonical name extension is the cluster name.

<cluster-name>.<domain-name>

For example:

test-cluster.example.com
Reserving IP addresses for nodes with the DHCP server

For the baremetal network, a network administrator must reserve a number of IP addresses, including:

  1. Three virtual IP addresses.

    • One IP address for the API endpoint

    • One IP address for the wildcard Ingress endpoint

    • One IP address for the name server

  2. One IP Address for the provisioner node.

  3. One IP address for each Control Plane (Master) node.

  4. One IP address for each worker node.

The following table provides an exemplary embodiment of hostnames for each node in the OpenShift Container Platform cluster.

Usage Hostname IP

API

api.<cluster-name>.<domain>

<ip>

Ingress LB (apps)

*.apps.<cluster-name>.<domain>

<ip>

Nameserver

ns1.<cluster-name>.<domain>

<ip>

Provisioner node

provisioner.<cluster-name>.<domain>

<ip>

Master-0

openshift-master-0.<cluster-name>.<domain>

<ip>

Master-1

openshift-master-1.<cluster-name>-.<domain>

<ip>

Master-2

openshift-master-2.<cluster-name>.<domain>

<ip>

Worker-0

openshift-worker-0.<cluster-name>.<domain>

<ip>

Worker-1

openshift-worker-1.<cluster-name>.<domain>

<ip>

Worker-n

openshift-worker-n.<cluster-name>.<domain>

<ip>

Configuring nodes

Each node in the cluster requires the following configuration for proper installation.

A mismatch between nodes will cause an installation failure.

While the cluster nodes can contain more than two NICs, the installation process only focuses on the first two NICs:

NIC

Network

VLAN

NIC1

provisioning

<provisioning-vlan>

NIC2

baremetal

<baremetal-vlan>

NIC1 is a non-routable network (provisioning) that is only used for the installation of the OpenShift Container Platform cluster.

The Red Hat Enterprise Linux (RHEL) 8.1 installation process on the provisioner node may vary. To install RHEL 8.1 using a local Satellite server or a PXE server, you may PXE-enable NIC2.

PXE

Boot order

NIC1 PXE-enabled provisioning network

1

NIC2 baremetal network. PXE-enabled is optional.

2

Ensure PXE is disabled on all other NICs.

Configure the Control Plane (master) and worker nodes as follows:

PXE

Boot order

NIC1 PXE-enabled (provisioning network)

1

Out-of-band management

Nodes will typically have an additional NIC used by the Baseboard Management Controllers (BMCs). These BMCs must be accessible from the provisioner node.

Each node must be accessible via out-of-band management. The provisioner node requires access to the out-of-band management network for a successful OpenShift Container Platform 4 installation.

The out-of-band management setup is out of scope for this document. We recommend setting up a separate management network for out-of-band management. However, using the provisioning network or the baremetal network are valid options.

Required data for installation

Prior to the installation of the OpenShift Container Platform cluster, gather the following information from all cluster nodes:

  • Out-of-band management IP

    • Examples

      • Dell (iDRAC) IP

      • HP (iLO) IP

  • NIC1 (provisioning) MAC address

  • NIC2 (baremetal) MAC address

Validation checklist for nodes

  • NIC1 VLAN is configured for the provisioning network.

  • NIC2 VLAN is configured for the baremetal network.

  • NIC1 is PXE-enabled on the provisioner, control plane (master), and worker nodes.

  • NIC2 is PXE-enabled when using a local PXE or Satellite server to install OS images.

  • PXE has been disabled on all other NICs.

  • Control Plane (master) and worker nodes are configured.

  • All nodes accessible via out-of-band management.

  • A separate management network has been created. (optional)

  • Required data for installation.